The present invention is directed generally to routing data among many possible points, and more particularly to a virtual optoelectronic crossbar switch.
The unprecedented growth in bandwidth is being facilitated by advances in optoelectronic technology. The increasing bandwidth of the internet which is causing data traffic to expand  greater than 200% per year has enabled higher performance from the peripheral networks. [Optoelectronic Industry Develop Assoc., Broadband Communications Technology Workshop, Palo Alto, Calif., April, 1999.] These include premises systems such as local area networks (LANs) and storage area networks (SANs) which implement Gigabit Ethernet (GbE), 10 GbE, and Fibre Channel protocols. The delivery of ultra-high band-width directly to the end user at the desktop over premises based networks remains a challenge using conventional switching architectures. As real-time applications are required, reducing the end-to-end latency is a primary problem which must be addressed in all networks. For example, high capacity network backbones are not available for on-demand service. In addition, high speed Internet transmission cannot be maintained without incurring packet loss.
Conventional optoelectronic crossbars require a central switching apparatus and choose to implement the address decode optically. This approach is inefficient and expensive.
The above and other problems and disadvantages of previous optoelectronic crossbar switches are overcome by the present invention of a virtual optoelectronic crossbar switch comprising a plurality of processor nodes, a plurality of optical paths, wherein each of the processor nodes includes a plurality of vertical cavity surface emitting laser diodes, one or more photodetectors; and a resonant cavity waveguide grating coupler positioned to couple light from the plurality of optical paths into the one or more photodetectors, and to couple light from the plurality of vertical cavity surface emitting laser diodes into the plurality of optical paths.
In another embodiment of the present invention, a network controller is provided which communicates with each of the plurality of processor nodes, and each of the plurality of processor nodes includes an address decoder which communicates with the network controller, and which enables ones of the plurality of vertical cavity surface emitting laser diodes in response to addresses from the network controller. Each of the plurality of vertical cavity surface emitting laser diodes is coupled by the resonant cavity waveguide grating coupler to a different one of plurality of optical paths, and a single photodetector is coupled to an assigned optical path.
In a still further embodiment of the present invention, for each of the plurality of processor nodes each of the plurality of vertical cavity surface emitting laser diodes is coupled by the resonant cavity waveguide grating coupler to a different one of plurality of optical paths. A first of the one or more photodetectors is coupled to an assigned optical path, and others of the one or more photodetectors are coupled to a different one of the plurality of optical paths and detect traffic on the assigned optical path.
In a further embodiment of the present invention, the plurality of optical paths are located in a single physical medium, and for each of the plurality of processor nodes each of the plurality of vertical cavity surface emitting laser diodes operate at different wavelengths, and the photodetectors are resonance cavity detectors.
In still another embodiment of the present invention, each of the plurality of processor nodes further includes additional pluralities of vertical cavity surface emitting laser diodes, wherein each of the plurality of vertical cavity surface emitting laser diodes in the additional groups operate at different wavelengths. Also provided are additional pluralities of photodetectors, wherein each photodetector in the additional pluralities of photodetectors groups is a resonant cavity enhanced photodetector responsive to a different wavelength.
The virtual optoelectronic crossbar switch of the present invention can significantly enhance end-to-end performance so that bandwidth-intensive applications can be realized. The virtual crossbar switch of the present invention is designed to eliminate central switching within a network while distributing the crossbar components. The virtual crossbar can be integrated into a LAN, metro network, WAN (wide area network) or SAN configuration for high speed networking. The age of xe2x80x9cnetwork-centricxe2x80x9d computing has furthered the need for fiber optic links [C. DeCusatis, Optical Engineering, Vol. 37, No. 12, pp. 3082-3099, December, 1998]. Due to the complex graphics which generate large files, LAN systems are being forced to their limits [3 P. Lombardi, Telecommunications (International Edition), Vol. 33, No. 4, pp. 41-42, April, 1999].
FIG. 1 shows a virtual crossbar LAN configuration 10 in accordance with the present invention where the central switch has been eliminated. Unlike most premises based networks which consist of a hierarchy of central switches and servers, in the present invention the optical fiber 12 becomes the network. This optoelectronic configuration is particularly useful for high speed applications such as 10 GbE because the switching is implemented with zero latency across the network. Users will be able to achieve high-speed end-to-end delivery, extremes in network flows, and zero latency. The virtual crossbar allows the network to be scalable as the number of users increases. Scalability will be achieved by incorporating the company""s parallel (N3) and global (N4) optical interconnect topology which utilizes high fan-in and fan-out as well as wavelength division multiplexing (WDM).
Additional tangible benefits to end users include full optical transparency, a large fully non-blocking reconfigurable crossbar, distributed cost, wide bandwidth per channel, dedicated channel interconnect, and adaptability to IP/WDM protocols. The virtual optoelectronic crossbar switch of the present invention also provides complementary hybrid optical/electronic systems and components that will remove network bottlenecks between the host and the bus. Considerable technical leverage in the network industry will be realized because the virtual crossbar will allow users to cost effectively upgrade their existing premises systems to achieve backbone functionality at the desktop. For new systems, it will provide a low cost approach to achieve high speed network functionality for fiber optic premises based networks. Several virtual optoelectronic system architectures have been developed which utilize optoelectronic integrated circuit (OEIC) device technologies as well as the VCSEL waveguide structure in accordance with the present invention.
These and other objectives, features and advantages of the present invention will be more readily understood upon considering the following detailed description of the invention and accompanying drawings.